Generally, an LCD device is being widely used due to its characteristics such as a light weight, a thin thickness, and a low power consumption. Recently, application fields of the LCD device are expanded to a portable computer such as a notebook PC, office automation equipment, and audio/video apparatus.
In the LCD device, a desired image is displayed on a screen by controlling an optical transmittance according to image signals applied to a plurality of switching controllers arranged in a matrix form.
The LCD device comprises an LC panel including a color filter substrate which is an upper substrate, a thin film transistor (TFT) array substrate which is a lower substrate, and an LC layer disposed between the two facing substrates; and an LC panel driving portion for driving the LC panel by supplying scan signals and image signals to the LC panel.
According to arrangement forms of liquid crystals and electrodes for applying an electric field to the liquid crystals, the LCD device is classified into an ECB (Electrically Controlled Birefringence) mode LCD device, a VA (Vertical Alignment) mode LCD device, a TN (Twisted Nematic) mode LCD device, and an IPS (In Plane Switching) mode LCD device.
Among the various types, the ECB mode and the TN mode LCD devices have a disadvantage that a viewing angle is narrow. On the contrary, the VA mode and the IPS mode LCD devices have an advantage that a viewing angle is wide. Accordingly, the VA mode and IPS mode LCD devices for a wide viewing angle are being widely practised.
However, the VA mode and the IPS mode LCD devices may cause the following problems. For example, when the VA mode and the IPS mode LCD devices are used for a user's personal purpose, the user's privacy may be damaged by his neighbors. Furthermore, when the VA mode and the IPS mode LCD devices are used for a confidential business, the confidential contents may be leaked out.
So as to solve the problems related to security, an LCD device for selectively implementing a display mode between a narrow viewing angle mode and a wide viewing angle mode has been proposed.
Hereinafter, the LCD device for selectively implementing a display mode between a narrow viewing angle mode and a wide viewing angle mode will be explained in more detail.
As shown in FIG. 1A, the LCD device for selectively implementing a display mode between a narrow viewing angle mode and a wide viewing angle mode is provided with an LC panel constituted with first, second, and third substrates 8, 11 and 9.
Referring to FIGS. 1A and 1B, the first substrate 8 serves as a color filter substrate. RGB color filters 3 that define RGB sub-pixels 2, and black matrixes 4 are formed on a transparent substrate 1. Here, one group composed of each one line of the RGB sub-pixels 2 defines one sub-pixel line 7. That is, the RGB sub-pixel line 7 corresponds to one vertical line of the RGB sub-pixels 2.
The second substrate 11 serves as a barrier substrate having barriers 5 for controlling a viewing angle. The second substrate 11 is attached to one surface of the first substrate 8 where the black matrixes 4 and the color filter 3 are not formed. The barriers 5 formed at the second substrate 11 are alternately formed above one RGB sub-pixel line 7 among a plurality of the RGB sub-pixel lines 7. More concretely, the barriers 5 are formed above one RGB sub-pixel line 7, but are not formed above an adjacent RGB sub-pixel line 7. Again, the barriers 5 are formed next to the adjacent RGB sub-pixel line 7. The pattern is repeatedly formed. Here, the barriers 5 entirely overlap an entire upper portion of the corresponding sub-pixel line 7, and partially extend to upper portions of adjacent sub-pixel lines 7 in right and left directions.
Although not shown, the third substrate 9 serving as a thin film transistor (TFT) array substrate includes gate and data lines that define RGB sub-pixels 2 by crossing each other on the transparent substrate, TFTs formed at each sub-pixel 2, and pixel electrodes.
As shown in FIG. 2A, when the conventional LCD device is to be operated in a narrow viewing angle mode, the RGB sub-pixels 2 having the barriers 5 thereabove are not operated, but the RGB sub-pixels 2 not having the barriers 5 thereabove are operated. On the contrary, as shown in FIG. 2, when the conventional LCD device is to be operated in a wide viewing angle mode, all the RGB sub-pixels 2 are operated.
However, in the conventional LCD device, most of the upper portions of the RGB sub-pixel 2 are shielded by the barriers 5, thereby decreasing an aperture ratio and thus lowering a brightness of a display screen.
Also, in the conventional LCD device for selectively implementing a display mode between a narrow viewing angle mode and a wide viewing angle mode, the second substrate 11 serving as a barrier substrate is provided thus to increase manufacturing costs.
Furthermore, in order to space the color filter 3 formed at the first substrate 8 and the barriers 5 formed at the second substrate 11 from each other, required are a process for etching one surface of the first substrate 8 where the black matrixes 4 and the color filter 3 are not formed, and a process for attaching the first substrate 8 and the second substrate 11 to each other.